<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Stage 3</title>
</head>
<body>

  <script src="module_a.js"></script>
  <script src="module_b.js"></script>
  <script>
    moduleA.fma(1)
    // 外部无法访问私有成员
    // console.log(moduleA.vma) // undefined

    moduleB.fmb(2)
  </script>
</body>
</html>